HR: 0800h
AN: H31A-1272    [Abstracts]
TI: Bedrock landscape evolution modeling: calibration using geochronology and DEM analysis
AU: * DeLong, S B
EM: sdelong@geo.arizona.edu
AF: Department of Geosciences, University of Arizona, 1040 E 4th Street, Tucson, AZ 85721 United States
AU: Pelletier, J D
EM: jon@geo.arizona.edu
AF: Department of Geosciences, University of Arizona, 1040 E 4th Street, Tucson, AZ 85721 United States
AU: Arnold, L
EM: lee.arnold@st-peters.oxford.ac.uk
AF: Oxford Luminescence Research Group, School of Geography and the Environment, University of Oxford, Mansfield Rd, Oxford, OX1 3TB United Kingdom
AB: Stream-power-based models of bedrock landscape evolution are effective at producing realistic synthetic topography but are difficult to calibrate. This paper examines ways in which field observations and DEM data can be used to calibrate bedrock landform evolution models for specific study sites. We first show how uplift rate U, bedrock erodibility K, and landslide threshold-slope Sc are related to steady-state relief, hypsometry, and drainage density for a wide range of synthetic topographies produced by a three-dimensional stream-power-based landscape-evolution model. We also extracted morphologic indicators as a function of time for a developing landscape to determine how these indicators behave before steady-state is achieved. We observe that hypsometric integral and mean elevation lowers as steady-state is approached, and drainage density increases. These observations allowed us to identify transient topography, quantify dynamics of transient landscape behavior and apply our model to less-than-ideal actual topography. Our results indicate that low U/K values result in low-relief, high-drainage-density, fluvially-dominated topography, and high U/K values lead to high-relief, low drainage density, mass-wasting-dominated topography. Realistic topography occurs for only a relatively narrow range of U/K between 10 and 5000 m kyr/kyr. Using measured values for the hyposmetric integral, drainage density and relief, the U/K value can be further constrained (enabling K to be determined if U is independently known).
DE: 1130 Geomorphological geochronology
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
DE: 1824 Geomorphology: general (1625)
DE: 1847 Modeling
SC: Hydrology [H]
MN: Fall Meeting 2005